The senior or eldest female member of a group, especially one who is most or highly respected.
A female doyen.
A woman who is highly experienced and knowledgeable in a particular field, subject, or line of work; expert
The most important one out of a related group.
The ship occupied by the fleet's commander (usually an admiral); it denotes this by flying his flag.
The ship regarded as most important out of a group, e.g. a nation's navy or company's fleet.
To act as a flagship for.